@article{MZM_1991_50_1_a9,
     author = {V. V. Rybakov},
     title = {Semantic admissibility criteria for deduction rules in $\mathbf{S4}$ and $\mathbf{Int}$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {84--91},
     publisher = {mathdoc},
     volume = {50},
     number = {1},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1991_50_1_a9/}
}